Controlling electric apparatus



S pt. 13, 1927. I ,398

M. BUCHHOLZ CONTROLLING ELECTRIC APPARATUS Original Filed Sept. 15 1922iffy I Patented Sept. 13, 1927.

UNITED STATES m BUOHHOLZ, O1? CASS EL, mm.

CONTROLLING ELECTRIC APPARATUS.

Oriinll application filed September 15,1822, Serial No. 588,457, and inAustria July 4, 1922. Divided and this application filed April 18, 1925.Serial No. 23,671.

My invention has reference to a method and means for protecting electricapparatus operating in an insulating liquid, such as oil transformers,oil switches, grounding throt- 5 tling coils, resistances and the like,and it is one of the important ob'ects of my lnvention to provide adevice 0 very simple construction and great reliability, and adapted tooperate before extensive injuries to in the apparatus to be protectedcan occur by sparking, overloading or other disturbances.

My invention is particularly based on the fact that in the case ofdisturbances in the 1?) operation of the apparatus to be protected or inthe case of spar ing or other irregularities of operation, or wheneversuch irregularities are imminent, as well as in the case of anyebullition or fermentation processes 20,in the oil, servin as aninsulating liquid, bubbles of gases of decomposition are formed whichcan operate protective means, for instance an electric contact, either aworking or a closed contact, which is adapted to switch out of circuitthe apparatus to be protected, or which will operate an alarm orannunciator device indicating the disturbance, or which is adapted toeffect both kinds of operations. The gases formed by decomposition mayinfluence the protective means in different ways, this applicationconstituting a division of my co-pending application Serial No. 588,457,filed September 15, 1922.

I may for instance utilize a variation of the specific gravity of theinsulating liquid occurring in consequence of the unnormal conditions ofworking mentioned above to vary the operative conditions of theprotective circuit.

A protective device embodying this invention is illustrated in thedrawings annexed to this specification by way of ex ample in a purelydiagrammatic manner in elevation.

In the drawings a is a transformer casing, 12 is the core of thetransformer, c are the windings, d are the leading-in insulations forthe conductors, e is an oil switch with a releasing coil f and g is asource of current which, upon the operation of the safety device,excites the coil, opens the oil switch and causes the switching-out ofthe apparatus.

s is a tubular extension mounted on the top of the transformer vessel a.As shown in the drawing, the vessel a is completely filled with oil andthe extension 8 is also filled with oil. This extension is open on topand a cylindrical float 1" partly immersed in the oil freely projectsfrom the extension. Underneath and in close proximity to the bottom ofthe float 'r there are arranged the two contacts In of the protectivecircuit comprising the source of current 9 and the coil f of the oilswitch.

If unnormal conditions of working such as spoken of above cause theformation of small bubbles of gases, vapors or fumes in the oilsurrounding the coils c of the transformer, these bubbles will rise inthe liquid and in ascending in the oil filling the extension 8 willcause a diminution of the specific gravity or in other words, a dilutionof the medium wherein the float r is floating. Obviously such diminutionof the specific gravity of the medium will cause the float r to sinkdeeper into the liquid, whereupon its bottom will come in contact withthe contact pieces-k whereby the protective circuit fed by the source 9will be closed and the coil 7 will be excited, thereby opening the oilswitch 0 and throwing out the apparatus.

The protective device according to this invention may be arranged atdifferent places, either in the interior of the main oil receptacle or,in the case of transformers, in combination with expansion vesselscontained therein, or special spaces, tubes or similar instrumentalitiesmay be provided adapted for the reception of the contacting devices. Theclosing of the circuit may be effected both Within as well as outside ofthe liquid.

The circuit to be controlled by the contacts referred to may exciteeither directly or by the medium of an intermediate relay the releasingcoil of an oil switch which interrupts the endangered circuit. In thecase of apparatus the circuit of which does not include an oil switch,as frequently occurs, for instance in the cases of transformers mountedin the field at wide distances apart, other provision should be made forthe purposes of this invention.

Besides the form of construction herein shown and described, theinvention is susceptible of a variety of other modifications and formsof application of the principle of my invention all of which 0 ratesubhe means of connecting the contacting device with the releasingcircuit and the switching means are open to changes and alterationswithout any material importance for the operation of the apparatusaccording to my invention which in its broad aspects comprises theoperation of safety devices for electric apparatus or the like, adaptedfor operation by vapors, fumes, gases or similar emanations liberatedand expelled from the insulating medium, and means adapted to be opera-vtively influenced by such emanations, and connected to fuses orequivalent safety means, the instrumentalities shown and described inthis specification as embodiments of these principles bein susceptibleof modifications Without deviating from the spirit of my invention asset forth in the claims.

In the claims the term gases is meant to comprise also vapors and fumes.

I claim 1. Protective system for liquid-insulated electric apparatuscomprising a container and a supply of insulating liquid, surroundingthe apparatus to be protected, a protective circuit and a contact deviceadapted to be operated by a variation of the specific gravity of part ofthe insulating liquid occurring in consequence of a decomposition ofsuch liquid, for varying the operative conditions of said circuit.

2. Protective system for liquid-insulated electric apparatus comprisinga container for said apparatus, a supply of i sulating liquid fillingsaid container and sur ounding said apparatus, a protective circuit, acontact included in the circuit and. a float partly submerged in saidliquid and adapted, on the specific gravity of said liquid beingdiminished by-gase's of decomposition developed therein, to descend andclose said contact.

3. Protective system for liquid insulated electric apparatus comprisinga container for said apparatus, a supply of insulating liquid fillingsaid container and surrounding decomposition occurring in the insulatingliquid due to abnormal conditions to vary the specific gravity of partof the liquid, and causing such variation to vary the operativeconditions of a protective circuit.

5. A protective system for liquid-insulated electric apparatuscomprising a container for said apparatus, a supply of insulating liquidcompletely filling saidcontainer and surroundin said apparatus, aprotective circuit, a tubular extension Vertically mounted on top of andcommunicating with said container and containing a column of insulatingliquid and a contact device immersed in the column of liquid in saidextension and adapted to be actuated by variations of the physical stateof said liquid for varying the operative conditions of said circuit.

6. A protective system for liquid-insu

